The changes in my memory were more life changing for me than diabetes- and y'all know diabetes was a game changer.
I don't know for certain whether or not diabetes was responsible, but I suspect it was.
Diabetes is associated with cognitive impairment in many domains as well as an increased risk of dementia in middle aged adults. DKA (which I was in at diagnosis) is associated with poorer cognitive performance for quite a while after the recovery from DKA.
I have read a lot of studies in which diabetics do a lot worse on cognitive tests and school performance; I've read others where there is no difference, and even a couple of studies where diabetics outperformed their siblings in school (maybe diabetes messed with sibling homelife, but the diabetics and not their siblings were given some slack in school?)
However, whatever the cognitive performance, diabetes undeniably is associated with brain changes visible on brain imagery:
And of course, diabetes increases risk of stroke.